The present invention relates to a needle selecting device for knitting machines or similar.
Knitting or stocking machines normally comprise a number of parallel needles arranged in the form of a cylinder and fitted to a support moving back and forth parallel to the needles. Depending on the pattern of the garment or stocking, at each operating cycle of the support, each needle is so selected as to accompany or not the movement of the support.
For this purpose, each needle is provided with a selector element having a cam portion engaged by the respective needle. The selector element is movable between two selection positions, in one of which the cam portion is positioned along the path of the respective needle; and, for enabling easy assembly on to the machine, selection assemblies are normally provided, each comprising a given number of selector elements.
Selection assemblies are known wherein each selector element is activated by a respective bistable electromagnet, e.g. with a movable core, which is moved to one or other of the two selection positions by a corresponding current pulse. The electromagnets normally present a response time in the region of 8-10 ms, which is far too slow and hence limits the output capacity of the machine.
To speed up operation of the machine, air-powered selection assemblies have been proposed which, despite providing for a response time of about 4 ms, are still relatively slow and, what more, invariably unreliable.